123 resources found

This paper details an experimental crown fire conducted in an Alberta, Canada, boreal black spruce forest to assess the effectiveness of recent crown thinning as a fuel treatment. Researchers ignited a 3. 6-hectare fire, observing its behavior in both untreated and thinned sections. The key finding was that while thinning led to a significant reduction in fire intensity, it did not reduce the fire's spread rate nor total fuel consumption. This suggests that in dense boreal black spruce with high surface fuel loads and low crown base heights, thinning alone may not prevent the rapid progression of crown fires, but it could potentially aid suppression efforts by reducing the intensity.

This study investigates how commercial thinning impacts the growth, yield, and mortality of natural lodgepole pine forests in Alberta, Canada. Faced with a predicted timber shortage due to fires and mountain pine beetle infestations, the research explores thinning as a strategy to increase mid-term sawlog supply by accelerating tree growth and enabling earlier timber access. The findings reveal that while thinned stands initially show less volume, they ultimately demonstrate a greater cumulative volume gain when factoring in the wood removed during thinning. This benefit stems from increased individual tree diameter and live crown ratio for remaining trees and a significant reduction in overall tree mortality, particularly among smaller trees.

This extension note outlines the successional pathways of various forest ecosystems in British Columbia and how these natural trajectories are influenced by natural disturbances, forest management practices, and projected climate change. The document describes typical post-disturbance development, the impacts of human interventions like harvesting, and potential future shifts due to altered temperature and precipitation regimes. The primary aim is to provide natural resource managers with a concise overview to inform strategies for building resistant and resilient forests in the face of ongoing environmental change.

This document investigates the long-term effects of pre-commercial stand thinning in lodgepole pine forests in British Columbia, specifically examining 30-year responses across a range of thinning densities. The central focus is on whether heavy thinning can simultaneously enhance forest productivity, measured by merchantable wood volume and carbon storage, and accelerate the development of old-forest structural attributes important for wildlife conservation. Findings revealed that heavy thinning did create large dominant trees with substantial crowns and other old-growth features, partially supporting the goal of restoration of old-forest structural attributes, and restored much of the lost carbon storage through crown growth. This study suggests that the structural complexity created by heavy thinning, rather than forest age alone, may be sufficient to sustain comparable total abundance, species richness, and diversity of forest-floor small mammals to that found in old-growth stands, highlighting a viable silvicultural approach to address timber needs and ecological restoration.

This FRDA Report #196 is a synthesis of project results investigating the effects of fertilization and thinning on a Douglas-fir ecosystem at Shawnigan Lake, British Columbia. The research reports on a long-term, multidisciplinary study examining how these forest management techniques influence tree growth, physiology, and ecosystem processes. Key themes include the long-term impact on growth and yield, the mechanistic response of the trees to nitrogen, and the fate of nitrogen fertilizers within the soil and water systems. This document provides a comprehensive overview intended to inform better forest management practices by synthesizing decades of experimental data.

This FRDA Report #029 details a long-term forestry study on the growth and yield of 56-year-old Western Hemlock stands in British Columbia, specifically examining the effects of commercial thinning over a 32-year period. The study found that while thinning did not significantly increase the overall cumulative yield, it did result in a larger average diameter for the remaining trees and an up to 8% greater usable total volume yield at the final harvest compared to unthinned stands. The decision to commercially thin these stands depends on whether a forester prioritizes a moderate increase in total volume or an improvement in the size and quality of the final harvested material.

This technical report evaluates how varying levels of aspen retention influence the development of mixed-species forest stands in British Columbia, specifically focusing on the growth of lodgepole pine and the emergence of aspen suckers. By comparing different thinning intensities against an untreated control, the researchers sought to identify thresholds for competition that allow for optimal timber production while maintaining the ecological benefits of broadleaf trees. The findings indicate that while pine vigour improved when fewer than 1000 aspen stems per hectare were kept, significant differences in tree height and diameter were not yet apparent four years after treatment. Additionally, the study confirms that complete aspen removal triggers the highest density of new suckering, whereas leaving residual trees helps suppress this regrowth. This document serves as a guide for silviculturists to refine free-growing standards and develop cost-effective management strategies for complex sub-boreal ecosystems.

This technical report evaluates a 14-year study on how clump thinning of bigleaf maple affects the development of both the maples and intermixed planted conifers in British Columbia. Because bigleaf maples regenerate via vigorous stump sprouting, they often overtop and outcompete young conifers, leading researchers to test whether reducing maple density could improve conifer survival and growth. The results revealed that manual thinning was largely ineffective for timber management, as the maple's rapid canopy closure and aggressive re-sprouting meant that the treatment provided no significant long-term growth advantage to the underlying conifers. Instead, the study suggests that bigleaf maple thrives under a coppice-based management system, where sprout growth is dictated more by internal clump dynamics than by the overall density of the stand. The authors conclude that while thinning does not benefit conifers, these mixedwood sites remain highly productive and may be better suited for short-rotation hardwood fiber production.

This document examines the growth and yield dynamics of a 14 year-old mixed-species plantation featuring Western redcedar and red alder in British Columbia. By comparing various planting ratios, the authors explore how complementary resource use affects tree development compared to single-species monocultures. The study reveals that while individual cedar growth improved in a balanced 50:50 mixture, the total stand productivity did not exceed that of pure stands, suggesting that mixtures offer benefits in biodiversity and wood quality rather than overall biomass volume. This document serves as a guide for forest managers to consider the ecological advantages of mixedwoods and provides a density threshold for maintaining conifer health when growing alongside alder.

This document examines a twenty-year study in British Columbia regarding the complex relationship between red alder and two conifer species, Douglas-fir and western redcedar. While alder is often removed by foresters because it competes for light and space, it also provides essential benefits by naturally fertilizing the soil with nitrogen. The findings suggest that maintaining a specific density of 100 to 200 alder trees per hectare can actually support conifer growth, particularly on nutrient-poor sites. The authors conclude that traditional forestry assessment methods may be inadequate, recommending a larger plot radius to more accurately measure how these different tree species interact and compete over time.

This document investigates how trembling aspen competition impacts the growth and survival of lodgepole pine within the Southern Interior Forest Region of British Columbia. By monitoring several forest sites over a seven-year period, researchers determined that tall aspen density is the most effective metric for predicting declines in pine diameter and overall vigor, likely due to competition for available light. The study reveals that pine performance drops significantly once aspen density exceeds specific ecological thresholds, which differ between the moist Sub-Boreal Spruce and the drier Interior Douglas-fir zones. This document serves as a management guide for foresters, offering scientific recommendations on the maximum amount of aspen that can be retained in young stands without compromising timber productivity.

This technical report evaluates the early effects of manipulating trembling aspen density on the development of lodgepole pine stands within the dry Interior Douglas-fir zone of British Columbia. By establishing an experiment near Meldrum Creek, researchers analyzed how different levels of aspen retention impacted conifer growth, vigor, and survival over a four-year period. The study found that while thinning immediately altered the stand structure and reduced aspen basal area, it did not yet yield significant improvements in pine performance, likely due to the young age of the trees and slow growth rates in this climate. Additionally, the report explores the competitive neighbourhood, identifying that aspen within a one-meter radius are the most influential competitors, while also noting that higher aspen retention may help suppress the density of new suckers. This research serves to refine competition thresholds and provide forest managers with biological data to optimize mixedwood management and free-growing guidelines in the region.

This document serves as a comprehensive manual for commercial thinning within the province of British Columbia, detailing how to manage intermediate harvests where the wood removed covers extraction costs. The text outlines a multi-level strategy that integrates strategic planning at the landscape level with specific stand selection criteria, such as windfirmness, tree stability, and forest health. Its primary purpose is to offer practitioners a framework for using thinning as a strategic management tool to increase wood flow flexibility, enhance timber value, and protect non-timber resource values like biodiversity and visual landscapes. Furthermore, the guidelines establish strict administrative and legal requirements under the Forest Practices Code, mandating detailed silviculture prescriptions and rigorous post-harvest assessments to monitor soil disturbance and residual tree damage.

This document examines how pre-commercial thinning influences the development of coastal Douglas-fir plantations in British Columbia. By evaluating seventeen years of data from various thinning regimes, the study demonstrates that reducing stand density significantly enhances the merchantable volume and diameter of individual trees. The author specifically recommends gradual thinning to a density of fewer than 1, 000 stems per hectare before the stand reaches thirty years of age to optimize sawlog production. This document serves as a practical guide for foresters, providing empirical evidence and growth simulation data to support more effective timber management strategies on medium-quality sites.

This document summarizes the early findings of a multidisciplinary study in Washington's Capitol Forest, which evaluates six different silvicultural regimes ranging from traditional clearcutting to group selection and untreated controls on an operational scale. By managing young-growth Douglas-fir stands for multiple objectives, researchers aim to provide forest managers with quantitative data on the biological, financial, and social consequences of various timber harvest patterns. Key themes include the comparative costs and feasibility of implementing these systems, the physical impact on soil and regeneration, and the public's aesthetic response to different landscape conditions. This study seeks to identify management options that can sustain high timber yields while simultaneously enhancing wildlife habitat and visual appeal to meet modern societal expectations.

This technical report evaluates the effectiveness of selection harvesting as an alternative to clearcutting within the old-growth temperate rainforests of Vancouver Island. By comparing single-tree and group selection methods, the study examines how these systems maintain an uneven-aged stand structure while meeting reforestation requirements on steep, ecologically sensitive terrain. The research highlights significant operational challenges, noting that safety regulations and the complexities of helicopter yarding often require foresters to adapt their initial harvesting prescriptions. This document concludes that while natural regeneration is abundant, the slow growth rates in shaded environments may require adjusted timelines for achieving free-growing status and long-term forest health.

This document evaluates the long-term effectiveness of dispersed tree retention as an alternative to clearcutting in the coast-interior transition zone of British Columbia. By monitoring a Douglas-fir forest near Boston Bar for fifteen years, the study examines how various levels of overstorey shading influence natural regeneration success, stand structure, and biological legacies. The data reveals that while residual trees enhance the micro-climate for new growth, they face significant mortality from windthrow, Douglas-fir bark beetle, and wildfire, leading to a substantial decline in living density over time. This document suggests that while dispersed retention provides valuable biodiversity attributes like snags and woody debris, an aggregated retention pattern might offer greater stability and protection against environmental stressors.

This document investigates the effectiveness of different harvesting methods for establishing Douglas-fir regeneration in the dry climate of British Columbia's interior. By comparing clearcutting against shelterwood systems, which retain partial tree canopies, the authors examine how varying levels of shade and protection influence the survival and size of new trees. The study found that while individual tree growth and crown volume were most robust in clearcut areas, the shelterwood treatments significantly improved the density of natural regeneration. This document suggests that a heavy-removal shelterwood may offer the ideal balance, providing adequate growth rates while acting as an insurance policy for a fully stocked forest.

This document is a part of a long-running Levels-of-Growing-Stock (LOGS) Cooperative Study in Douglas-fir stands, specifically detailing findings from installations at Sayward Forest and Shawnigan Lake in British Columbia. The core objective of the LOGS study is to understand how different thinning intensities impact cumulative wood production, individual tree size, and growth ratios in young Douglas-fir stands. This progress report summarizes data from these two Canadian sites, showing that volume growth is strongly tied to the amount of growing stock retained, and that thinning significantly influences tree size distribution and live crown development, suggesting potential for future productivity gains. The study also offers comparisons between various thinning regimes and unthhinned control plots, revealing the long-term implications of silvicultural practices on forest stands.

This document details a 15-year study examining the effects of partial cut logging, specifically single-tree selection harvesting, on dry-belt Douglas-fir stands in British Columbia. The research, initiated in 1993, investigated how different levels of residual growing stock and stand structure influenced the growth of remaining trees and the establishment of new seedlings. By remeasuring permanent plots and analyzing overstorey and understorey development, the study aimed to provide long-term data crucial for improving growth and yield models, informing sustainable forest management practices, and understanding the dynamics of these complex forest ecosystems.